The present invention relates to the removal of sulfur from carbonaceous materials, fuels, and fuel precursors (resources). The combustion of sulfur compounds in carbonaceous fuels produces pollutants in the form of acidic sulfur oxide gaseous emissions. Concern about the environmental impact of these pollutants has resulted in stricter regulations on allowable sulfur levels in fuels. The requirement for lower sulfur levels and the increased reliance on heavier high sulfur feedstocks will require increased refinery desulfurization capacity. Further, to achieve low fuel sulfur levels requires the removal of those compounds that resist conventional hydrodesulfurization, notably the sterically hindered dibenzothiophene compounds. Limitations on the ability of conventional hydrodesulfurization to remove these compounds, and the high cost of hydrogen, place great emphasis on the development of novel desulfurization technology.
Fossil fuels contain significant quantities of sulfur, largely in the form of organic sulfur containing molecules. Sulfur in fuels causes corrosion of transportation and processing equipment, fouling of processing catalysts and upon combustion, air pollution in the form of acidic gas emissions. The sulfur content of hydrocarbon feeds entering refineries has increased steadily over the last ten years exacerbating sulfur related problems. In the United States and abroad environmental concerns about sulfur related air pollution have resulted in more stringent regulations on the sulfur content of fuels. High sulfur refinery feeds combined with more stringent regulations place a great emphasis on the development of new methods to reach extremely low fuel sulfur levels.